1. Field of the Invention
This invention relates to the field of pencil plotters and, in particular, to an actuator mechanism for a pencil carriage in which the position of a lead holder and the lead therein are controlled both relative to one another and relative to a drawing media surface.
2. Description of Related Art
Pencil plotters are being used more increasingly in the making of graphics and drawings due to the ability of such graphics and drawings to be erased or to have alterations or corrections made thereto. In addition, the use of lead, rather than ink, in the plotters eliminates certain detrimental factors such as ink clogging up in the pen during the plotting process or drying up in the pen tip while the pen is held in a carousel waiting to be used. Nevertheless, certain precautions have to be taken in the use of pencil plotters to ensure an even and unwavering line or trace on the surface of the drawing media. These precautions entail, among other things, making sure that the lead holder is properly secured in a lead holder mechanism and that the lead itself is properly secured within the lead holder. Mechanisms for accomplishing the above are described in my copending patent applications, Ser. No. 07/834,967, filed Feb. 14, 1992, entitled "Finger Mechanism for a Lead Holder" now abandoned and Ser. No. 07,834,966, filed Feb. 14, 1992, entitled "Lead Holder Mechanism for a Pencil Plotter", assigned to the same assignee as the present invention. Another problem inherent in pencil plotters is ensuring that the lead carried by the lead holder is always in even contact with the surface of the drawing media.
Thus, it is a primary object of the present invention to provide an improved actuator mechanism for the pencil carriage of a pencil plotter.
It is another object of the present invention to provide an improved actuator mechanism in which an even and constant down force is applied to the lead.
It is a further object of the present invention to provide an improved actuator mechanism which is stable during the up/down cycle of the lead holder.
It is still another object of the present invention to provide an improved actuator mechanism which accurately controls the position of the lead and lead holder relative to one another and the surface of the drawing media during the plotting cycle.